Russians have been targeting routers--the hardware that allows communication between local home networks (read: personal computers and connected devices) and the internet. They're attempting to either seek control of the device or to hack into homes and small businesses, Ciaran Martin, the chief executive of Britain's National Cyber Security Center, told the Times.

But the threat may just be that, a threat. Officials were unsure of the extent of Russia's penetration of Western computer networks or the Kremlin's intent. One explanation offered by officials suggests that Russia could just be infiltrating systems as leverage in a coordinated attack down the road--that is, theft may not be the main goal, according to the Times.

Russia, for its part, denied the allegations."We consider these accusations and speculations as striking examples of a reckless, provocative, and unfounded policy against Russia," according to an email sent to Forbes from the Russian embassy in London. "We are disappointed by the fact that such serious claims have been made publicly, without any proof being presented and without any attempt by the United Kingdom to clarify the situation with the Russian side in the first place."

Kremlin spokesman Dmitry Peskov said Tuesday the accusations were "unsubstantiated and have no value," according to news agency Interfax.

Even so, it's wise to be cautious. The agencies offered guidance for individuals and businesses to ensure their networks are secure. Among other things, the advice included suggestions on making passwords more secure and better protecting devices.

While these steps may sound simple, doing nothing is not an option, say officials. "Once you own the router, you own all the traffic, to include the chance to harvest credentials and passwords," Howard Marshall, deputy assistant director of the cyber division at the FBI, told the Times. "It is a tremendous weapon in the hands of an adversary."